diff --git a/src/Config.py b/src/Config.py
index c14f2a58..4164a27a 100644
--- a/src/Config.py
+++ b/src/Config.py
@@ -220,7 +220,7 @@ class Config(object):
         self.parser.add_argument('--stream_downloads', help='Stream download directly to files (experimental)',
                                  type='bool', choices=[True, False], default=False)
         self.parser.add_argument("--msgpack_purepython", help='Use less memory, but a bit more CPU power',
-                                 type='bool', choices=[True, False], default=True)
+                                 type='bool', choices=[True, False], default=False)
         self.parser.add_argument("--fix_float_decimals", help='Fix content.json modification date float precision on verification',
                                  type='bool', choices=[True, False], default=fix_float_decimals)
         self.parser.add_argument("--db_mode", choices=["speed", "security"], default="speed")
diff --git a/src/Connection/Connection.py b/src/Connection/Connection.py
index baf50188..2cfdb27d 100644
--- a/src/Connection/Connection.py
+++ b/src/Connection/Connection.py
@@ -3,6 +3,7 @@ import time
 
 import gevent
 import msgpack
+import msgpack.fallback
 
 from Config import config
 from Debug import Debug
@@ -138,7 +139,7 @@ class Connection(object):
         self.connected = True
         buff_len = 0
 
-        self.unpacker = msgpack.Unpacker()
+        self.unpacker = msgpack.fallback.Unpacker()  # Due memory problems of C version
         try:
             while not self.closed:
                 buff = self.sock.recv(16 * 1024)
@@ -153,7 +154,7 @@ class Connection(object):
                 self.server.bytes_recv += buff_len
 
                 if not self.unpacker:
-                    self.unpacker = msgpack.Unpacker()
+                    self.unpacker = msgpack.fallback.Unpacker()
                 self.unpacker.feed(buff)
                 buff = None
                 for message in self.unpacker: